High pressure liquid chromatography selector valves typically employ a stator element and a rotor device with a fluid-tight seal at the rotor/stator interface therebetween. Selector valves are typically used to direct fluid along alternate flow paths. For example, alternate columns along a flow path can be selected using a selector valve.
One type of selector includes a disk shaped rotor with channels on its front face that face holes or ports in the rear face of the stator. Rotation of the rotor, which is rotated by a motor-driven shaft, allows channels to connect to different columns depending on the position of the valve. In a typical valve, selection may be limited to only two alternate paths. Another type of selector valve has a radial groove in the rotor and an additional center port in the stator. By rotating the rotor, connection of any number of radial ports can be alternately made to the common center port. However, for such a selector valve assembly, a second selector valve is needed to redirect the flow to the alternate path. Yet another type of selector valve, described in U.S. Pat. No. 5,803,117 (which is hereby incorporated herein for all purposes), provides a single selector valve that allows selection from among three alternate routes, using channels formed in the rotor face. The selector valve described in U.S. Pat. No. 5,803,117 is a dual selector valve that uses one half of the stator face for input ports and the other side of the stator face for output ports. This arrangement of ports results in fairly good dispersion, but poor port-packing density.
While these valves are reliable, efficient, and highly successful, they often have limited switching options due to the relatively small surface area of the rotor face and the path of the fluid channel, or two selector valves may be necessary for selecting among additional alternate paths. Typically, there is relatively little surface area on the rotor face to provided additional switching options. Accordingly, there is a need to provide a single selector valve that has additional functionality while minimizing the surface area of the rotor face.